(1) Field of the Invention
The present invention relates to frame forming apparatus and jigs therefor. More particularly the present invention relates to welding machines for welding corners or joints of frames such as window frames, for example, in which pairs of side elements of a window frame or a door frame, are positioned together to form a corner of the window frame or door frame, and the pair of elements are held in frame forming position and welded together forming all or part of the window, or door, frame.
(2) Description of the Prior Art
Prior to the use of plastics for making the structure of a window frame both wood or metal were used for making window and/or door frames. The frame elements or sides of window frames when made out of wood were secured by either an adhesive, nails, screws or some other connector, or a combination of two or more of the holding or connector components. When metals were used for the frame elements the pairs of frame elements were connected and held together by welding the corners together.
The welding of structural metal frames, such as steel, for example for support of equipment is well known. Elements of a frame are cut to size and contour, and positioned together to form a corner and an insert was usually welded to both elements to hold them in position, thus forming a corner. Some of the frame elements were very heavy and sometimes required, not only manual labor but sometimes required the use of auxiliary tables on which to initially locate the ends of the frame elements or sections to be welded.
Later elements of a frame were secured and supported on pivotable clamps which were adapted to lock into place and firmly hold the elements of the frame parts in proper relationship to each other in preparation for welding. Such fixture is more completely described in U.S. Pat. No. 3,054,887 issued Sept. 18, 1962.
Metal was also used in the frame elements for making window frames but the individual elements or sides of the frame used substantially light weight metal for the frame parts. However, since the frame elements had to be rigidly held in position for connecting the elements together to form the corners, essentially the same type of equipment used to form structural frames was used to form the much lighter window frames, except that the equipment itself was scaled down in size and capability.
With the development of stronger plastics, such as vinyl compounds, for example, frames, such as window frames and door frames were made from plastic elements. With the use of the less heavy plastic elements the handling of the elements with the heavy materials, dual tables and heavy jigs was avoided and light weight simple jigs were used to support and hold adjacent elements of the frames in position to be welded.
Commercial equipment is available which welds plastic elements of a frame, such as a window frame, for example, together to form a corner of the plastic frame. Single point and multi-point welding machines may be obtained in which corners of the same plastic frame may be welded, one at a time or more complex welding apparatus is available when more than one corner of the same frame is welded in the same operation. However, where technology has advanced in the materials used the handling of the elements forming the frames, has not kept technology with the advancement in materials used and although apparatus is available for forming, through a welding operation, more than one corner of the same window frame in a single operation the more complex frame element handling apparatus currently available is limited to the manufacture and handling of one frame at a time.